But long-term benefits of moderate alcohol consumption outweigh risks

Action Points

Note that this meta-analysis suggests an increased risk of stroke and myocardial infarction immediately following alcohol consumption.

Be aware that the study also showed longer-term protective effects of moderate alcohol consumption.

Drinking alcohol was linked to an immediate increase in heart attack and stroke risk in all drinkers, but moderate drinkers seemed to experience some protective cardiovascular benefits within 24 hours of imbibing, according to a systematic review and dose-response meta-analysis.

The analysis of 23 studies with a combined total of close to 30,000 participants suggested a roughly twofold acute increase in myocardial infarction (MI) and stroke risk occurring within the hour after drinking, Mostofsky told MedPage Today.

"Although there is a transiently higher risk, we saw a lower risk for heart attack and hemorrhagic stroke within a day of moderate drinking and a lower risk for ischemic stroke within a week," Mostofsky said. "This is perfectly consistent with what we have learned about the long-term health benefits of regular, moderate consumption."

Moderate alcohol consumption (about two to four drinks within 24 hours) has been shown in numerous studies to have long-term cardiovascular benefits, but the immediate impact of drinking alcohol on heart attack and stroke risk has not been widely studied, she said.

"Just after drinking, blood pressure rises and blood platelets become stickier, which may increase the risk of having a heart attack or stroke, but regular moderate alcohol consumption is associated with higher HDL cholesterol and reduced blood clotting, which may decrease risk," Mostofsky said.

However, heavy alcohol drinking was associated with higher cardiovascular risk in the following day (six to nine drinks) and week (19-30 drinks).

The researchers searched multiple databases for observational studies assessing the association between alcohol intake and cardiovascular events in the hours and days following consumption. They were able to calculate pooled relative risks (RR) and confidence intervals for the association between alcohol intake and MI, ischemic stroke (IS), and hemorrhagic stroke (HS) using DerSimonian and Laird random-effects models to model any alcohol intake, or dose-response relationships of alcohol intake and cardiovascular events.

The dose-response meta analysis revealed that moderate alcohol consumption was associated with an immediately higher cardiovascular risk that was attenuated after 24 hours, and protective for MI and hemorrhagic stroke (RR=30% lower risk), and protective against ischemic stroke within 1 week (about six drinks, RR=9% lower risk).

Heavy alcohol consumption was associated with higher cardiovascular risk in the following day (RR=1.3-2.3) and week (RR=2.25-6.2).

Compared with no alcohol consumption, moderate drinkers (about 75 g of alcohol or about six drinks/week) had a 19% lower risk for ischemic stroke, while heavy drinkers (19 to 30 drinks/week) had a 2.25-fold to six-fold higher ischemic stroke risk, with the risk increasing as alcohol consumption increased.

A U-shaped association with consumption level was also seen for MI, with the greatest benefit seen with approximately 28 g (about two drinks) a day (RR=0.67) and the highest risk seen with around 108 g (about nine drinks).

The findings add to the evidence that a drinker's total alcohol consumption and pattern of drinking impact the cardiovascular risks and benefits associated with alcohol consumption.

"Heavy episodic drinking, defined as 4 or more alcoholic beverages within 1 to 2 hours has harmful effects, even if individuals who binge only drink one or two days per week, resulting in the same average alcohol intake per week that is known to yield cardioprotective benefits," the researchers wrote.

They cited the heterogeneous nature of the included studies as a limitation of the analysis, along with a lack of data on several relevant factors, including alcohol type (beer, wine, liquor).

"Despite these limitations, this study is the first attempt to understand comprehensively the interplay between dose and timing of alcohol intake and the immediate risks and benefits on both MI and stroke," they wrote.

The study was funded by the NIH, the Harvard Catalyst/Harvard Clinical and Translational Science Center, the Danish Cancer Society, and Danish Council for Strategic Research.